1. Field of the Invention
The present invention relates to a digital camera, and more particularly to a digital camera that avoids blurring of a photograph which may be caused by movement of the camera when the photograph is taken.
2. Discussion of the Background
As digital cameras for taking a high quality photographs continue to improve, the demand for avoiding blurring of photographs due to camera movement is accordingly increasing. Japanese Patent Laid-Open Publication No. 58481/1992 describes a related digital video camera having a blur compensating device for compensating for blurring of a photograph caused by movement of the camera when the photograph is taken. The video camera of JP No. 58481/1992 includes a solid-state imager with a variable speed shutter, a shutter speed control device which changes a shutter speed of the imager, and a control device which synchronously controls the blur compensating device and the shutter speed control device. The digital video camera is configured such that the shutter speed is changed in cooperation with an operation of the blur compensating device and thereby the degradation of an image resolution of the photograph due to the blurring is avoided.
However, the electronic circuit for the blur compensating device of JP 58481/1992 is rather complicated, and the constitution of the digital video camera is complicated due to this circuit. As a result, the cost of the camera is increased, and moreover the size of a body of the camera is relatively large. In addition, power consumption of the camera is increased due to this circuit, which inevitably reduces the battery duration time for the camera.
Accordingly, it is an object of the present invention to provide a novel and improved digital camera that avoids blurring of a photograph which may be caused by movement of the camera when the photograph is taken with a simple constitution at a low cost.
It is another object of the present invention to reduce the power consumption of the camera for enabling a long battery operation of the camera with a compact body.
It is another object of the present invention to simplify the structure of a blur compensating device for a digital camera for decreasing the overall body size of the camera, for reducing the power consumption of the camera so as to enable a longer duration time with the battery operation, and for reducing the production cost of the camera.
The above and other objects are achieved according to the present invention by providing a new and improved method, system and computer readable medium for controlling a digital camera including setting a shutter speed; receiving a light flux from an object to be photographed to form an image thereof at the set shutter speed; converting the received light flux into an image signal; amplifying the image signal with a variable gain; judging whether or not the shutter speed is set slower than a predetermined blur avoiding speed; and increasing the variable gain to a predetermined value when the shutter speed is set slower than the predetermined blur avoiding speed.
Another embodiment includes a method, system and computer readable medium for controlling a digital camera including setting a shutter speed; receiving a light flux from an object to be photographed to form an image thereof at the set shutter speed; converting the received light flux into an image signal; amplifying the image signal with a variable gain; judging whether or not the shutter speed is set slower than a predetermined blur avoiding speed; selectively setting a photographing mode to one of: a blur avoiding photographing mode in which the variable gain is increased to a predetermined value when the shutter speed is set slower than the predetermined blur avoiding speed, and a normal photographing mode in which the variable gain is not increased even when the shutter speed is set slower than the predetermined blur avoiding speed; and increasing the variable gain to a predetermined value when the blur avoiding photographing mode is set and when the shutter speed is set slower than the predetermined blur avoiding speed.